Degradation of boscalid, pyraclostrobin, fenbuconazole, and glyphosate residues by an advanced oxidative process utilizing ultraviolet light and hydrogen peroxide

Recently an advanced oxidative process (AOP) combining H2O2 and UV-C light was observed to be effective at controlling Listeria monocytogens and Escherichia coli O157:H7 and degrading chlorpyrifos residues on the surface of apples. Little is known about the application of AOP for the degradation of other pesticide residues. This study examined degradation of boscalid, pyraclostrobin, fenbuconazole and glyphosate by 3% (w/v) H2O2, UV-C (254 nm) irradiation and their combination on apple skin and glass. The extent of degradation was not significantly different between the AOP and optimal individual treatment. However, treatment susceptibility was different with glyphosate most effectively degraded by H2O2 exposure (up to 98 % on apple, 3% (w/v) H2O2 at 30 °C for 15 min) while boscalid, pyraclostrobin and fenbuconazole were more effectively degraded by UV-C (up to 88 %, 100 % and 70 % degradation after ∼11,000 mJ/cm2). Suggestions for possible causes of degradation are proposed.